Electrolytic method of refining iron.



A. S. RAMAGE.

ELECTROLYTIC METHOD OF REFINING IRON.

APPLIOATION FILED MAR. 7, 1911.

1,007,388. Patented Oct. 31. 1911.

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ALEXANDER S. RAMAGE, OF BUFFALO, NEW YORK.

ELECTROLYTIC METHOD OF REFINING IRON.

Specification of Letters Patent.

Patented Oct. 31, 1911.

Application filed March 7, 1911'. Serial No. 612,795.

To all whom it may concern:

Be it known that I, ALEXANDER S. RAMAGE, a. citizen of the UnitedStates, residing at Buffalo, in the county of Erie and State of NewYork, have invented certain new and useful Improvements in ElectrolyticMethods of Refining Iron, of which the following is a specification.

This invention relates to the electrolytic refining of impure iron, theobject of the invention being the provision of a method whereby iron ofhigh purity and substantially free from carbon may be prepared fromimpure forms of the metal, such for example as cast or wrought ironscrap, castiron turnings or borings, impure sponge, or the like. y

In the practice of processes for the electrolytic refining of ironwherein the impure iron is employed as the soluble anode, it has provenimpossible to avoid the contamination of the cathodic deposit by certainimpurities derived from the iron, notably carbon and certain metals,such as arsenic and antimony, whose sulfids are insoluble in dilute acidsolutions. According to the present process this difiiculty is obviatedby preparing the solutions for electrolysis by dissolving the impureiron outside of the electrolytic cell, and under conditions avoiding thesolution of such metals as are liable to contaminate theelectrodeposited iron.

In order that the invention may be fully understood, I will describe thesame by reference to the accompanying drawings, wherein the figure is amerely diagrammatic representation of steps.

111' the preferred embodiment of the invention, I provide anelectrolytic cell 1, divided by a diaphragm 2 of asbestos cloth or othersuitable material into anode and cathode compartments 3 and 4. Theanodes 5 may be of sheet-lead and the cathodes 6 of iron. If a solutionof ferrous sulfate be electrolyzed in both compartments of a cell ofthis character, iron will be deposited at the cathodes, while ferricsulfate and sulfuric acid will be formed in the region of the anode.

The electrolytic cell may be of any preferred type, its specificconstruction forming no part of the present invention; and the number ofanode and cathode compartments may be multiplied as desired. Thecathodes may be either stationary or revolving, the revolving cathodespermitting the employment of much higher current dens1t1es, as is wellunderstood in the art.

From the anode compartments of the electrolytic cells the acid liquor ispermitted to flow into a suitable tank or scrubber 7, wherein it issubjected to the action of a small pro ortion of sulfur dioxid. Thepurpose 0 this treatment is merely to form sufiicient sulfuric acid toreplace that lost through leakage or from other mechanical causes, andthe amount of sulfur dioxid introduced should in no case be suflicientto effect the reduction of the ferric sulfate to ferrous sulfate. Theacid liquor passes then to a solution tank 8, wherein it is brought intocontact with impure iron, such as iron scrap, cast-iron turnings,detinned scrap, reduced iron sponge, or the like, together with somesulfid, usually ferrous sulfid, which under the action of the acidliquor will gene-rate hydrogen sulfid. Under these conditions, and inthe acid liquor, there occurs a complete precipitation of those metalswhose sulfids are insoluble in dilute acids. The solution of the impureiron is preferably aided by heat, and preferably also the solution tankis fitted with an insoluble anode buried in the scrap and contactingtherewith, and with an iron cathode in the liquor above the scrap, theeffect of this arrangement being to aid in the solution of the scrapiron and to diffuse the hydrogen throughout the solution. The hydrogen,and the sulfureted hydrogen resulting from the solution of the addedsulfid, effect the reduction of the ferric sulfate to ferrous sulfate.

In practice, two or more solutlon tanks of similar construction areprovided, one of these receiving the flow of liquid while the other isreacting on the scrap and thereby becoming neutralized. When the liquorhas become practically neutral it is forced through a filter-press 9,flowing thence to a mixing tank 10, wherein it is mixed with theefliuent liquor from the cathode compartments. The mixed liquor flows toa storage tank 11, whence it is distributed to the several anode andcathode compartments of the electrolytic cells, thus completing thecycle of operations.

The sulfid of iron used in the solution tank should be sufiicient inquantity for the complete precipitation of such metallic sulfids as areinsoluble in the acid solution, the actual proportion of sulfiddepending of course upon the character of the impure metal. Thetemperature of the liquors is preferably maintained throughout the cycleabove normal, the preferred temperature during electrolysis beingapproximately 145 1 When stationary cathodes are employed a currentdensity approximating 10 amperes per square foot is found suitable, thevoltage under these conditions approximating 2.5 volts per cell. Withthe use of revolving cathodes, current densities approximating 100ampcres per square foot may be used, the voltage being accordinglyincreased.

I claim:

1. The method of refining iron by electrolysis, which consists inelectrolytically dissolving impure iron in an acid ferric liquor, andthereafter electrolyzing the resulting ferrous liquor in a cell providedwith a diaphragm and insoluble anodes, whereby a cathodic deposit ofiron of high purity is obtained.

2. The method of refining iron by electrolysis, which consists indissolving impure iron in an acid ferric liquor while avoiding solutionof metals whose sulfids are insoluble in dilute mineral acids, andthereafter electrolyzing the resulting ferrous liquor, using insolubleanodes, whereby a cathodic deposit of iron of high purity is obtained.

3. The method of refining iron by electrolysis, which consists inelectrolytically dissolving impure iron in an acid ferric liquor whileavoiding solution of metals whose sulfids are insoluble in dilutemineral acids, and thereafter electrolyzing the resulting ferrousliquor, using insoluble anodes, whereby a cathodic deposit of iron ofhigh purity is obtained.

4. The cyclical method of refining iron by electrolysis, which consistsin electrolyzing a solution of a ferrous salt in a cell provided with adiaphragm and insoluble anodes, neutralizing the anode liquor andreducing the ferric salt therein by reaction with impure iron, combiningthe resulting ferrous solution with the eflluent cathode liquor, andreturning the combined liquors to the electrolytic cell.

5. The cyclical method of refining iron by electrolysis, which consistsin electrolyzing a solution of a ferrous salt in a cell provided with adiaphragm and insoluble anodes, reacting on the anode liquor with sulfurdioxid without effecting complete reduction thereof, neutralizing saidanode liquor and reducing the ferric salt therein by reaction withimpure iron, combining the resulting ferrous solution with the ellluentcathode liquor, and returning the combined liquors to the electrolyticcell.

6. The cyclical method of refining iron by electrolysis, which consistsin electrolyzing a solution of a ferrous salt in a cell provided with adiaphragm and insoluble anodes, neutralizing the anode liquor andreducing the ferric salt therein by reaction with impure iron inpresence of ferrous sulfid, combining the resulting ferrous solutionwith the eflluent cathode liquor, and returning the combined liquors tothe electrolytic cell.

7 The cyclical method of refining iron by electrolysis, which consistsin electrolyzing a solution of a ferrous salt in a cell provided with adiaphragm and insoluble anodes, reacting on the anode liquor with sulfurdioxid without effecting complete reduction thereof, neutralizing saidanode liquor and reducing the ferric salt therein by reaction withimpure iron in presence of ferrous sulfid, combining the resultingferrous solution with the efiiuent cathode liquor, and returning thecombined liquors to the electrolytic cell.

In testimon whereof, I aflix my signature in presence 0 two witnesses.

ALEXANDER S. RAMAGE.

Witnesses:

CHARLES F. HOUCK, FRED. C. HOUOK.

